物理牛頓運動定律 DSE、CE 選擇題（第 10 頁）

91.

Which of the following motions of a given mass requires the greatest force $P$ ? (Assume that the surface is smooth.)

Four cases: A upward acceleration 0 on a 30 degree slope, B upward acceleration 1 m/s2 on 30 degrees, C acceleration 0 on 60 degrees, D acceleration 1 m/s2 on 60 degrees

92.

Spring S attached to a wall and a 2 kg block on a table, string over two pulleys supporting a 6 kg block

The system of pulleys and blocks is at rest. What is the tension in string $S$ ? (Neglect all friction and the masses of the strings and pulleys.)

93.

Hand pulling with a 10 N spring balance, string T1 to block A, string T2 to block B on a smooth surface

Two blocks $A$ and $B$ of masses $1$ kg and $1.5$ kg respectively are resting on a smooth horizontal surface and are linked by a string. They are pulled by a force of $10$ N as shown in the diagram. What are the tensions $T_1$ and $T_2$ ?

	Tension $T_1$	Tension $T_2$
	$10$ N	$10$ N
	$10$ N	$6$ N
	$10$ N	$4$ N
	$6$ N	$4$ N

94.

Block given an initial velocity up a smooth inclined plane

A block is given an initial velocity up a smooth inclined plane. Which graph below shows the acceleration of the block against time ? (The upward direction of motion along the plane is taken as positive.)

95.

If the engine of a rocket travelling in space is turned off, the rocket will

96.

A person in a lift, which is ascending at a velocity of $10\ \mathrm{m\,s^{-1}}$ , releases a ball. What is the velocity of the ball with respect to the earth at the moment when the ball is released ?

97.

The net force acting on a particle is zero. Which of the statements below concerning the motion of the particle may be true ?

98.

The graph shows the variation of velocity $v$ with time $t$ when a metal ball is released from rest and allowed to fall vertically under gravity through oil. Which of the following statements concerning the motion of the ball is/are correct ?

(1)The velocity of the ball decreases with time.

(2)The acceleration of the ball decreases with time.

(3)The ball stops falling after

4

s.

Velocity against time graph rising from 0 and levelling off at 10 m/s by about 4 s

99.

A trolley on a smooth horizontal surface is pulled by two forces $P$ and $Q$ in the direction as shown in the figure. The magnitudes of $P$ and $Q$ are $2$ N and $1$ N respectively. If the mass of the trolley is $1$ kg, the acceleration of the trolley is

Trolley pulled by force P at 30 degrees above the horizontal to the right and force Q horizontally to the left

100.

A body of mass $M$ rests in equilibrium on a plane inclined at an angle $\theta$ to the horizontal. What is the frictional force acting on the body ?

Block M at rest on a plane inclined at angle theta